A clean room must have a ceiling that prevents the entrance into the room of impermissible dirt particles. The standard hard ceiling of a room generally will not suffice for this purpose. Additionally, the passage into the clean room of required services such as electricity, plumbing, and ventilation often proceeds through the clean room's ceiling. All of these factors generally tend to indicate the use of a dropped, suspended ceiling for a clean room.
The dropped ceilings that have found use for clean rooms, however, display serious limitations. These ceilings have generally required the permanent installation of a structure including the usual ceiling components which include electrical fixtures, ventilating units and tiles. This on-site construction involves a substantially higher cost that the use of prefabricated regular ceilings. Additionally, these individually designed and constructed ceilings, of course, would not have utility at different locations or in different rooms.
Additionally, the permanently installed ceilings do not provide facile ingress of the required services such as electrical, plumbing, and communication. Furthermore, they also do not have a convenient manner of providing room sprinklers when a particular installation requires them.
Further, clean rooms may fall within the moderately strict requirements down to class 100 (i.e. not more than 100 particles of 0.5 microns in size per cubic foot of air) which may use a dry seal, such as a gasket, to hold ceiling components. Drastically cleaner rooms below class 100 generally require a wet seal utilizing petroleum jelly to prevent the flow of air. Present clean rooms do not permit the facile interchange from one type of room to another.
Accordingly, the search continues for a suspended ceiling for a clean room that can utilize prefabricated components. Moreover, it should allow the facile ingress of the required services. Desirably, the ceiling should readily undergo the interchange between differing standards of cleanliness as the room's use requires.